The present invention relates to polymers having enhanced hydrophilicity and thermal regulative properties and a process of producing the same.
Many polymers such as aliphatic polyamide polymers (e.g., nylon) and polyester polymers are inherently hydrophobic. Fabrics formed entirely from these polymers tend to exhibit poor moisture absorption and release properties and fail to provide thermal regulative properties. Typically in apparel fabrics, comfort is obtained by blending the aliphatic polyamide or polyester polymer fibers with hydrophilic fibers such as cotton fibers.
There are also various recognized methods for enhancing the hydrophilicity of the polymer. For example, aliphatic polyamide and polyester polymers can be treated with appropriate hydrophilic add-on agents or coatings. However, these add-on agents or coatings have not met with widespread acceptance particularly due to the lack of permanence under repeated laundering conditions.
Another method of enhancing hydrophilicity is the preparation of graft polymers of aliphatic polyamide and polyester polymers and appropriate hydrophilic comonomers. For example, U.S. Pat. No. 4,135,877 to Aikawa et al. proposes the graft polymerization of water-soluble vinyl monomers such as acrylic acid, acrylamide and N,N'-methylene-bisacrylamide onto polyamide fibers using heat and an aqueous treating solution containing acid. The graft polymerization of hydrophobic vinyl monomers with nylon, polypropylene and polyesters is proposed in U.S. Pat. No. 3,297,786 to Horowitz. See, also, for example, U.S. Pat. Nos. 3,099,631 to Tanner; 3,097,185 to Armen et al.; 3,252,880 to Magat et al.; and 3,278,639 to Matray. These graft polymerization techniques, however, often alter the structure of the aliphatic polyamide and polyester polymers. This can be counterproductive in that such altering of the structure results in the loss of other physical properties of the polymer such as hand, fabric strength and thermal regulative properties.
Despite the general availability of various add-on chemicals and graft polymerization techniques for improving hydrophilicity, there continues to be a desire for method improvements for enhancing the hydrophilicity and thermal regulative properties of polymers, particularly aliphatic polyamide and polyester polymers, and fibers and fabrics formed therefrom. For example, improvements in the retention of the hydrophilicity can improve the extended wearability and washability properties of the fabric made using the polymers. Adverse affects to other properties such as hand, fiber and fabric strength, flammability, etc. also must be avoided. The processing steps also must be controllable and not require additional steps to remove contaminants from the polymer or from the processing equipment.
It is therefore an object of the present invention to provide a polymer (e.g., aliphatic amide or polyester polymers) having enhanced hydrophilicity and thermal regulative properties, and a process for providing the same.